According to The Sacramento Bee,

Kreycik went for a 6- to 8-mile run Saturday morning, July 10, 2021, in the park and left his wallet and phone inside his car, McClatchy News previously reported. He didn’t return home.

Kreycik’s wife phoned police hours after Kreycik was supposed to come back, KRON4 reported.

Pleasanton police said they were worried because temperatures reached triple digits on Saturday and search teams, including scent hounds, were called to look for Kreycik, according to NBC Bay Area.

One of the dogs found Kreycik’s scent and followed it from his car to the trail but lost track, the station reported.

Kreycik has been described as an “endurance athlete” in “top physical condition” who is used to “rural terrain and outdoor environments,” Alameda County Sheriff’s officials said in a Facebook post. Temperatures reached 106 degrees Saturday but they weren’t “a deterrent” for Kreycik who “thrives in extreme environments,” authorities said.

More than 100 search-and-rescue members have looked for Kreycik over the past four days and drones, dogs, helicopters and an airplane with thermal imagery have also been used, officials said.